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Article

Predictive Model of Setting Times and Compressive Strengths for Low-Alkali, Ambient-Cured, Fly Ash/Slag-Based Geopolymers

1
School of Materials Science and Engineering, UNSW Sydney, Sydney 2052, Australia
2
NMR Facility, Mark Wainwright Analytical Centre, UNSW Sydney, Sydney 2052, Australia
3
School of Civil and Environmental Engineering, UNSW Sydney, Sydney 2052, Australia
4
School of Civil and Environmental Engineering, University of Technology, Sydney 2007, Australia
*
Author to whom correspondence should be addressed.
Minerals 2020, 10(10), 920; https://doi.org/10.3390/min10100920
Received: 16 August 2020 / Revised: 4 October 2020 / Accepted: 5 October 2020 / Published: 17 October 2020
The effects of curing temperature, blast furnace slag content, and Ms on the initial and final setting times, and compressive strengths of geopolymer paste and mortars are examined. The present work demonstrates that ambient-cured geopolymer pastes and mortars can be fabricated without requiring high alkalinity activators or thermal curing, provided that the ratios of Class F fly ash (40–90 wt%), blast furnace slag (10–60 wt%), and low alkalinity sodium silicate (Ms = 1.5, 1.7, 2.0) are appropriately balanced. Eighteen mix designs were assessed against the criteria for setting time and compressive strength according to ASTM C150 and AS 3972. Using these data, flexible and reproducible mix designs in terms of the fly ash/slag ratio and Ms were mapped and categorised. The optimal mix designs are 30–40 wt% slag with silicate modulus (Ms) = 1.5–1.7. These data were used to generate predictive models for initial and final setting times and for ultimate curing times and ultimate compressive strengths. These projected data indicate that compressive strengths >100 MPa can be achieved after ambient curing for >56 days of mixes of ≥40 wt% slag. View Full-Text
Keywords: geopolymers; ambient curing; low alkalinity; setting time; compressive strength geopolymers; ambient curing; low alkalinity; setting time; compressive strength
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MDPI and ACS Style

Ukritnukun, S.; Koshy, P.; Rawal, A.; Castel, A.; Sorrell, C.C. Predictive Model of Setting Times and Compressive Strengths for Low-Alkali, Ambient-Cured, Fly Ash/Slag-Based Geopolymers. Minerals 2020, 10, 920. https://doi.org/10.3390/min10100920

AMA Style

Ukritnukun S, Koshy P, Rawal A, Castel A, Sorrell CC. Predictive Model of Setting Times and Compressive Strengths for Low-Alkali, Ambient-Cured, Fly Ash/Slag-Based Geopolymers. Minerals. 2020; 10(10):920. https://doi.org/10.3390/min10100920

Chicago/Turabian Style

Ukritnukun, Supphatuch, Pramod Koshy, Aditya Rawal, Arnaud Castel, and Charles C. Sorrell. 2020. "Predictive Model of Setting Times and Compressive Strengths for Low-Alkali, Ambient-Cured, Fly Ash/Slag-Based Geopolymers" Minerals 10, no. 10: 920. https://doi.org/10.3390/min10100920

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